1. Field of the Invention
The present invention relates to a liquid crystal display device in which transistors are provided in respective pixels, and a manufacturing method thereof. The present invention also relates to a light-emitting display device in which transistors are provided in respective pixels, and a manufacturing method thereof.
2. Description of the Related Art
In recent years, a metal oxide having semiconductor characteristics, which is called an oxide semiconductor, has attracted attention as a novel semiconductor material having both high mobility almost the same as that of crystalline silicon and uniform element characteristics almost the same as those of amorphous silicon. The metal oxide is used for a variety of applications. For example, indium oxide is a well-known metal oxide and used as a material of a light-transmitting pixel electrode included in a liquid crystal display device or the like. Examples of such metal oxides having semiconductor characteristics include tungsten oxide, tin oxide, indium oxide, and zinc oxide. Transistors in each of which a channel formation region is formed using such a metal oxide having semiconductor characteristics have been known (Patent Documents 1 and 2).